Even if you're in the grip of the muse and the words are flowing like cheap hooch at an Irish wedding (I'm Irish before you get offended), stop before you finish. If you can bring yourself to do it, stop in the middle of a sentence. Using the Slaughtered Lamb Entrail Method™, you'll find that you're keen to get back to the page when your next day's writing session begins. Moreover, you won't be stuck at the beginning of a new scene, staring at the flashing Cursor of Doom and wondering what happens next. You'll always have something to pick up and run with.

I've heard that tip before as well, and it actually is really helpful advice. Although, as with all tips, it's only as useful as you personally find it. Tons more writing tips at the link. [Tor UK]